The Bcl2-associated anthanogene (BAG) 3 protein is a member of the BAG family of cochaperones, which supports multiple critical cellular processes, including critical structural roles supporting ...desmin and interactions with heat shock proteins and ubiquitin ligases intimately involved in protein quality control. The missense mutation P209L in exon 3 results in a primarily cardiac phenotype leading to skeletal muscle and cardiac complications. At least 10 other Bag3 mutations have been reported, nine resulting in a dilated cardiomyopathy for which no specific therapy is available. We generated αMHC-human Bag3 P209L transgenic mice and characterized the progressive cardiac phenotype in vivo to investigate its utility in modeling human disease, understand the underlying molecular mechanisms, and identify potential therapeutic targets. We identified a progressive heart failure by echocardiography and Doppler analysis and the presence of pre-amyloid oligomers at 1 year. Paralleling the pathogenesis of neurodegenerative diseases (eg, Parkinson disease), pre-amyloid oligomers–associated alterations in cardiac mitochondrial dynamics, haploinsufficiency of wild-type BAG3, and activation of p38 signaling were identified. Unexpectedly, increased numbers of activated cardiac fibroblasts were identified in Bag3 P209L hearts without increased fibrosis. Together, these findings point to a previously undescribed therapeutic target that may have application to mutation-induced myofibrillar myopathies as well as other common causes of heart failure that commonly harbor misfolded proteins.
The assessment of river channels widely focusses on using channel form to identify channel character but fails to capture the more nuanced variations in morphodynamics without the analysis of ...process. This paper presents a method using an index of channel behaviour, the throughput ratio (ζ), which is calculated from morphologic change and sediment transport, and explores the viability of inferring process from channel form to act as an indicator of channel behaviour. Two experiments using the same initial width, slope, discharge, and grain size were used to demonstrate the effectiveness of this method in representing different morphodynamics. In one experiment the channel was allowed to laterally deform, whilst the other had inerodible elements placed at its boundaries. As a result the experiment with mobile banks widened and reduced sediment transport to zero, whereas the fixed-bank experiment – unable to decrease its shear stress – continued to output material. In both, the rate of morphologic change tended to zero despite their marked differences in sediment transport over time. The differences in evolution are due to the differences in process available to each channel despite an initial similarity in bed mobility and their gross similarity of a meandering planform. The throughput ratio allows new representations of the temporal and spatial patterns of the morphodynamics, providing additional measures with which to analyse the processes acting in river channels.
Alveolar-capillary leak is a hallmark of the acute respiratory distress syndrome (ARDS), a potentially lethal complication of severe sepsis, trauma and pneumonia, including COVID-19. Apart from ...barrier dysfunction, ARDS is characterized by hyper-inflammation and impaired alveolar fluid clearance (AFC), which foster the development of pulmonary permeability edema and hamper gas exchange. Tumor Necrosis Factor (TNF) is an evolutionarily conserved pleiotropic cytokine, involved in host immune defense against pathogens and cancer. TNF exists in both membrane-bound and soluble form and its mainly -but not exclusively- pro-inflammatory and cytolytic actions are mediated by partially overlapping TNFR1 and TNFR2 binding sites situated at the interface between neighboring subunits in the homo-trimer. Whereas TNFR1 signaling can mediate hyper-inflammation and impaired barrier function and AFC in the lungs, ligand stimulation of TNFR2 can protect from ventilation-induced lung injury. Spatially distinct from the TNFR binding sites, TNF harbors within its structure a lectin-like domain that rather protects lung function in ARDS. The lectin-like domain of TNF -mimicked by the 17 residue TIP peptide- represents a physiological mediator of alveolar-capillary barrier protection. and increases AFC in both hydrostatic and permeability pulmonary edema animal models. The TIP peptide directly activates the epithelial sodium channel (ENaC) -a key mediator of fluid and blood pressure control- upon binding to its α subunit, which is also a part of the non-selective cation channel (NSC). Activity of the lectin-like domain of TNF is preserved in complexes between TNF and its soluble TNFRs and can be physiologically relevant in pneumonia. Antibody- and soluble TNFR-based therapeutic strategies show considerable success in diseases such as rheumatoid arthritis, psoriasis and inflammatory bowel disease, but their chronic use can increase susceptibility to infection. Since the lectin-like domain of TNF does not interfere with TNF's anti-bacterial actions, while exerting protective actions in the alveolar-capillary compartments, it is currently evaluated in clinical trials in ARDS and COVID-19. A more comprehensive knowledge of the precise role of the TNFR binding sites versus the lectin-like domain of TNF in lung injury, tissue hypoxia, repair and remodeling may foster the development of novel therapeutics for ARDS.
Clinical evidence suggests that statins reduce cancer incidence and mortality. However, there is lack of in vitro data to show the mechanism by which statins can reduce the malignancies of cancer ...cells. We used a human B lymphoma Daudi cells as a model and found that lovastatin inhibited, whereas exogenous cholesterol (Cho) stimulated, proliferation cell cycle progression in control Daudi cells, but not in the cells when transient receptor potential canonical 6 (TRPC6) channel was knocked down. Lovastatin decreased, whereas Cho increased, the levels of intracellular reactive oxygen species (ROS) respectively by decreasing or increasing the expression of p47-phox and gp91-phox (NOX2). Reducing intracellular ROS with either a mimetic superoxide dismutase (TEMPOL) or an NADPH oxidase inhibitor (apocynin) inhibited cell proliferation, particularly in Cho-treated cells. The effects of TEMPOL or apocynin were mimicked by inhibition of TRPC6 with SKF-96365. Lovastatin decreased TRPC6 expression and activity via a Cho-dependent mechanism, whereas Cho increased TRPC6 expression and activity via an ROS-dependent mechanism. Consistent with the fact that TRPC6 is a Ca2+-permeable channel, lovastatin decreased, but Cho increased, intracellular Ca2+ also via ROS. These data suggest that lovastatin inhibits malignant B cell proliferation by reducing membrane Cho, intracellular ROS, TRPC6 expression and activity, and intracellular Ca2+.
•Lovastatin inhibits, whereas cholesterol stimulates, lymphoma proliferation via TRPC6.•Lovastatin inhibits, whereas cholesterol stimulates, both NOX2 and TRPC6 expression.•Superoxide and TRPC6 control lymphoma cell proliferation.•Lovastatin decreases, whereas cholesterol increases, intracellular Ca2+via TRPC6.
Epithelial sodium channels (ENaCs) located at the apical membrane of polarized epithelial cells are regulated by the second messenger guanosine 3',5'-cyclic monophosphate (cGMP). The mechanism for ...this regulation has not been completely characterized. Guanylyl cyclases synthesize cGMP in response to various intracellular and extracellular signals. We investigated the regulation of ENaC activity by natriuretic peptide-dependent activation of guanylyl cyclases in Xenopus 2F3 cells. Confocal microscopy studies show natriuretic peptide receptors (NPRs), including those coupled to guanylyl cyclases, are expressed at the apical membrane of 2F3 cells. Single-channel patch-clamp studies using 2F3 cells revealed that atrial natriuretic peptide (ANP) or 8-(4-chlorophenylthio)-cGMP, but not C-type natriuretic peptide or cANP, decreased the open probability of ENaC. This suggests that NPR-A, but not NPR-B or NPR-C, is involved in the natriuretic peptide-mediated regulation of ENaC activity. Also, it is likely that a signaling pathway involving cGMP and nitric oxide (NO) are involved in this mechanism, since inhibitors of soluble guanylyl cyclase, protein kinase G, inducible NO synthase, or an NO scavenger blocked or reduced the effect of ANP on ENaC activity.
Social media has transformed the way health messages are communicated. This has created new challenges and ethical considerations while providing a platform to share nutrition information for ...communities to connect and for information to spread. However, research exploring the web-based diet communities of popular diets is limited.
This study aims to characterize the web-based discourse of popular diets, describe information dissemination, identify influential voices, and explore interactions between community networks and themes of mental health.
This exploratory study used Twitter social media posts for an online social network analysis. Popular diet keywords were systematically developed, and data were collected and analyzed using the NodeXL metrics tool (Social Media Research Foundation) to determine the key network metrics (vertices, edges, cluster algorithms, graph visualization, centrality measures, text analysis, and time-series analytics).
The vegan and ketogenic diets had the largest networks, whereas the zone diet had the smallest network. In total, 31.2% (54/173) of the top users endorsed the corresponding diet, and 11% (19/173) claimed a health or science education, which included 1.2% (2/173) of dietitians. Complete fragmentation and hub and spoke messaging were the dominant network structures. In total, 69% (11/16) of the networks interacted, where the ketogenic diet was mentioned most, with depression and anxiety and eating disorder words most prominent in the "zone diet" network and the least prominent in the "soy-free," "vegan," "dairy-free," and "gluten-free" diet networks.
Social media activity reflects diet trends and provides a platform for nutrition information to spread through resharing. A longitudinal exploration of popular diet networks is needed to further understand the impact social media can have on dietary choices. Social media training is vital, and nutrition professionals must work together as a community to actively reshare evidence-based posts on the web.
Regulating ENaC's gate Kleyman, Thomas R; Eaton, Douglas C
American Journal of Physiology: Cell Physiology,
01/2020, Letnik:
318, Številka:
1
Journal Article
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Odprti dostop
Epithelial Na
channels (ENaCs) are members of a family of cation channels that function as sensors of the extracellular environment. ENaCs are activated by specific proteases in the biosynthetic ...pathway and at the cell surface and remove embedded inhibitory tracts, which allows channels to transition to higher open-probability states. Resolved structures of ENaC and an acid-sensing ion channel revealed highly organized extracellular regions. Within the periphery of ENaC subunits are unique domains formed by antiparallel β-strands containing the inhibitory tracts and protease cleavage sites. ENaCs are inhibited by Na
binding to specific extracellular site(s), which promotes channel transition to a lower open-probability state. Specific inositol phospholipids and channel modification by Cys-palmitoylation enhance channel open probability. How these regulatory factors interact in a concerted manner to influence channel open probability is an important question that has not been resolved. These various factors are reviewed, and the impact of specific factors on human disorders is discussed.
With no lysine (WNK) kinases are members of the serine/threonine kinase family. We previously showed that WNK4 inhibits renal large-conductance Ca(2+)-activated K(+) (BK) channel activity by ...enhancing its degradation through a lysosomal pathway. In this study, we investigated the effect of WNK1 on BK channel activity. In HEK293 cells stably expressing the α subunit of BK (HEK-BKα cells), siRNA-mediated knockdown of WNK1 expression significantly inhibited both BKα channel activity and open probability. Knockdown of WNK1 expression also significantly inhibited BKα protein expression and increased ERK1/2 phosphorylation, whereas overexpression of WNK1 significantly enhanced BKα expression and decreased ERK1/2 phosphorylation in a dose-dependent manner in HEK293 cells. Knockdown of ERK1/2 prevented WNK1 siRNA-mediated inhibition of BKα expression. Similarly, pretreatment of HEK-BKα cells with the lysosomal inhibitor bafilomycin A1 reversed the inhibitory effects of WNK1 siRNA on BKα expression in a dose-dependent manner. Knockdown of WNK1 expression also increased the ubiquitination of BKα channels. Notably, mice fed a high-K(+) diet for 10 days had significantly higher renal protein expression levels of BKα and WNK1 and lower levels of ERK1/2 phosphorylation compared with mice fed a normal-K(+) diet. These data suggest that WNK1 enhances BK channel function by reducing ERK1/2 signaling-mediated lysosomal degradation of the channel.
The detailed single-channel gating kinetics of mouse pannexin 1 (mPanx1) remains unknown, although mPanx1 is reported to be a voltage-activated anion-selective channel. We investigated ...characteristics of single-channel conductances and opening and closing rates of mPanx1 using patch-clamp techniques. The unitary current of mPanx1 shows outward rectification with single-channel conductances of ~20 pS for inward currents and ~80 pS for outward currents. The channel open time for outward currents (Cl
influx) increases linearly as the amplitude of single channel currents increases, while the open time for inward currents (Cl
efflux) is constant irrespective of changes in the current amplitude, as if the direction and amplitude of the unitary current regulates the open time. This is supported by further observations that replacement of extracellular Cl
with gluconate
diminishes the inward tail current (Cl
efflux) at a membrane potential of -100 mV due to the lowered outward current (gluconate
influx) at membrane potential of 100 mV. These results suggest that the direction and rate of charge-carrier movement regulate the open time of mPanx1, and that the previously reported voltage-dependence of Panx1 channel gating is not directly mediated by the membrane potential but rather by the direction and amplitude of currents through the channel.
Summary Objective To examine use of complementary and alternative medicine (CAM) among individuals with radiographic-confirmed osteoarthritis (OA) of the knee. Methods We included 2679 participants ...of the Osteoarthritis Initiative with radiographic tibiofemoral knee OA in at least one knee at baseline. Trained interviewers asked a series of specific questions relating to current OA treatments including CAM therapies (seven categories – alternative medical systems, mind-body interventions, manipulation and body-based methods, energy therapies, and three types of biologically based therapies) and conventional medications. Participants were classified as: (1) conventional medication users only, (2) CAM users only; (3) users of both; and (4) users of neither. Polytomous logistic regression identified correlates of treatment approaches including sociodemographics and clinical/functional correlates. Results CAM use was prevalent (47%), with 24% reporting use of both CAM and conventional medication approaches. Multi-joint OA was correlated with all treatments (adjusted odds ratios (aOR) conventional medications only: 1.62; CAM only: 1.37 and both: 2.16). X-ray evidence of severe narrowing (OARSI grade 3) was associated with use of glucosamine/chondroitin (aOR: 2.20) and use of both (aOR: 1.98). The Western Ontario and McMaster Universities (WOMAC)-Pain Score was correlated with conventional medication use, either alone (aOR: 1.28) or in combination with CAM (aOR: 1.41 per one standard deviation change). Knee Outcomes in Osteoarthritis Survey (KOOS)-Quality of Life (QOL) and Short Form (SF)-12 Physical Scale scores were inversely related to all treatments. Conclusion CAM is commonly used to treat joint and arthritis pain among persons with knee OA. The extent to which these treatments are effective in managing symptoms and slowing disease progression remains to be proven.
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